Corrosion behaviour of some stainless steels in chloride solutions

ABSTRACT

The pitting corrosion of various types of stainless steels was studied in different anions. The effect of temperature was also examined. The most well known aggressive anion is the chloride ion. The open circuit potential and the potentiodynamic techniques were used. The pitting potential, Ep and the protection potential, Epp were determined for stainless steels.The pitting and protection potentials depend linearly on the concentration of Cl - ion according to the equations. Ep = a + b log [Cl -]. Epp=a -+b - log [Cl -]. Pitting potential is shifted to more negative values with the increase of Cl - content, as well as the temperature according to the composition of the alloy. The concentration necessary for pitting and the critical pitting temperature increases with increasing Cr content. The effect of different concentrations of SO 4 -2 ion at temperature up to 80°C was also investigated